Voltage detector for hydraulic lifts

ABSTRACT

A voltage detector assembly employed in hydraulic systems, comprising a hydraulic power unit having a hydraulic cylinder with a piston, a hydraulic fluid reservoir connected with the hydraulic cylinder and containing hydraulic fluid, a pump operated by a motor connected with the hydraulic fluid reservoir. The hydraulic fluid reservoir includes a pair of control valves and a pair of relief valves. A battery is connected to the hydraulic power unit by means of a start solenoid that transfers power from the battery to the motor of the hydraulic power unit. A digital remote having a circuit board, a digital display, an up button and a down button, is connected to the hydraulic power unit and the battery through the start solenoid. The digital display registers available battery power in volts during upstroke and down stroke of the hydraulic system.

RELATED APPLICATIONS

Not Applicable.

BACKGROUND OF THE DISCLOSURE

1. Technical Field of the Disclosure

The present embodiment is related in general to voltage detectors, andin particular to a voltage detector switch utilized for monitoringvoltage across the terminals of a battery connected with a hydraulicsystem.

2. Description of the Related Art

Hydraulic systems enable an operator to accomplish significant work(lifting heavy loads, turning a shaft, drilling precision holes, etc.)with a minimum of mechanical linkage. Battery-operated hydraulic systemsare found in a wide variety of applications, from small assemblyprocesses to integrated steel and paper mill applications. Thesehydraulic power systems offer convenience and versatility, in connectionwith utility vehicles, utility units, utility trailers and otherhydraulically powered equipment. Many operators prefer a battery-poweredhydraulic system as it replaces manual pumping by the operator toactuate the hydraulics and, thus involve less physical effort. After aperiod of continued operation or non-use of hydraulic systems, thebattery loses voltage. Currently, the operator has no way of knowing thestatus of the battery when operating the hydraulic systems. Thus, thebattery voltage can drop below the minimum voltage level for operation,and continued operation can cause damage to other components. Damage mayinclude overflow of fluid from a reservoir tank, arcing across thecontact points which can melt the metal, cause damage to the startersolenoid, the melting of the insulation, increasing the currentproducing excessive heat, causing damage to the motor, and couldpotentially cause a fire. Therefore, one of the most criticalrequirements for battery-operated hydraulic systems is the developmentof a reliable and economical way to monitor battery functionality so asto increase the life and reduce potential damage of battery-poweredhydraulic systems. In addition another objective would be to identifythe status of battery readiness, which describes what the level of powera battery can deliver at any given moment.

The level of battery voltage is key to determining the operating stateof the battery. Battery monitoring also serves to protect medical,defense, and communication devices, as well as wheeled mobility andelectric vehicle applications. Battery monitoring allows the operator todetermine when the operation of the hydraulic system should be stopped,and when the battery needs to be charged to prevent damage to thehydraulic system.

One existing voltage detecting system provides an apparatus fordiagnosing a low voltage battery which includes a high voltage batteryfor powering an electric automobile, a voltage converter that reducesthe output of the high voltage battery to a low voltage, a low voltagebattery for powering the auxiliaries of the automobile, acurrent/voltage sensor, a controller, and a warning indicator. Thecontroller diagnoses the degradation of the low voltage battery at thestart of the operation of the automobile by referring the output of thecurrent/voltage sensor to a set of selected predetermined referencevalues.

Another existing system provides a handheld, wired remote control unitfor battery-operated hydraulic power systems. The remote control unitcomprises a hydraulic actuator command circuit, a battery level controlcircuit and an audio/visual operator assistance module. The batterylevel control circuit receives a control signal representative of acharge level of a battery that supplies energy to said actuator, andprocesses it. A battery cut-out circuit in the operator assistancemodule prevents operation of the actuator when the battery level is toolow.

Another existing battery voltage detector discloses a system and methodfor detecting low battery voltage supplied to a battery operatedintegrated circuit. A stable reference voltage provided by a bandgapreference is compared with the battery voltage. A switched capacitorcircuit is used instead of the more conventional resistor combination tosupply a scaled representation of the battery voltage. Powerrequirements are reduced by combining the bandgap reference and thecomparator into a single component.

However, the above-described voltage detector systems are complicated indesign and thus high in cost. Such voltage detector systems do notmonitor battery voltage in real time and thus do not prevent damage tothe hydraulic system in real time. Further, such systems do not preventarcing across the contact points and probable damage to the startersolenoid or the motor, creating a potential fire hazard. Moreover, suchsystems do not provide a signal when the battery needs to be charged.

In light of the foregoing, there is a need for a voltage detectionsystem that would detect the voltage across the battery terminals of abattery-powered hydraulic system. Such a needed system would give thestatus of the battery when operating the hydraulic system and leading tothe prevention of damage of the hydraulic system. Such a needed systemwould monitor the minimum voltage level to the hydraulic system in realtime and prevent the overflow of fluid from the reservoir tank. Thissystem would prevent arcing across the contact points and therebyprevent damage to the starter solenoid and the motor, and wouldeliminate a fire hazard. Such a needed system would allow a user todetermine when the operation of the hydraulic system should be stoppedand when the battery needs to be charged. Such a system would be costeffective, and help prevent damage to machinery, thus avoiding the needfor replacement of damaged parts. The present embodiment accomplishesthese objectives.

SUMMARY OF THE INVENTION

To minimize the limitations found in the prior art, and to minimizeother limitations that will be apparent upon the reading of thespecifications, the preferred embodiment of the present inventionprovides a hydraulic power unit with real time voltage detection.

The hydraulic power unit comprises a hydraulic fluid reservoircontaining a hydraulic fluid. The hydraulic fluid reservoir has a pairof control valves and a pair of relief valves. The pair of controlvalves includes a load holding valve and a directional control valve.The pair of relief valves includes a primary relief valve and asecondary relief valve. The hydraulic fluid reservoir is connected witha hydraulic cylinder with a rod end and a bore end. The hydrauliccylinder has a piston positioned inside. A pump operated by a motor isconnected with the hydraulic fluid reservoir. The pump pumps thehydraulic fluid from the hydraulic fluid reservoir to the hydrauliccylinder.

A battery is connected to the hydraulic power unit by means of a startsolenoid. A digital remote is further connected to the hydraulic powerunit and the battery through the start solenoid. The digital remote hasa digital display that registers available battery power in volts duringupstroke and down stroke of the hydraulic system power unit. The digitalremote informs the operator when the available power is insufficient tooperate the hydraulic power unit.

A first objective of the present invention is to provide abattery-powered hydraulic unit with a voltage detection assembly thatdetects the voltage across the battery terminals.

A second objective of the present invention is to provide a hydraulicunit that gives the status of the battery in real time during operationthereof.

A third objective of the present invention is to provide a hydraulicunit that prevents arcing across the contact points and thereby preventdamage to the start solenoid and the motor, and eliminates a firehazard.

Another objective of the present invention is to provide a hydraulicunit that allows a user to determine when operation should be stoppedand when the battery needs to be charged.

A further objective of the present invention is to provide a hydraulicunit that is cost effective, and avoids the need for replacement ofdamaged parts.

These and other advantages and features of the present invention aredescribed with specificity so as to make the present inventionunderstandable to one of ordinary skill in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Elements in the figures have not necessarily been drawn to scale inorder to enhance their clarity and improve understanding of thesevarious elements and embodiments of the invention. Furthermore, elementsthat are known to be common and well understood to those in the industryare not depicted in order to provide a clear view of the variousembodiments of the invention, thus the drawings are generalized in formin the interest of clarity and conciseness.

FIG. 1 is a front perspective view of a preferred embodiment of ahydraulic power unit;

FIG. 2 is a side perspective view of the preferred embodiment of thehydraulic power unit;

FIG. 3 is a perspective view of a digital remote connected to thehydraulic power unit;

FIG. 4 is a sectional view of the digital remote connected to thehydraulic power unit;

FIG. 5 is a schematic diagram of the hydraulic power unit; and

FIG. 6 is a schematic diagram illustrating the electrical connectionsbetween the hydraulic power unit and the digital remote.

DETAILED DESCRIPTION OF THE DRAWINGS

In the following discussion that addresses a number of embodiments andapplications of the present invention, reference is made to theaccompanying drawings that form a part hereof, and in which is shown byway of illustration specific embodiments in which the invention may bepracticed. It is to be understood that other embodiments may be utilizedand changes may be made without departing from the scope of the presentinvention.

Various inventive features are described below that can each be usedindependently of one another or in combination with other features.However, any single inventive feature may not address any of theproblems discussed above or only address one of the problems discussedabove. Further, one or more of the problems discussed above may not befully addressed by any of the features described below.

FIG. 1 is a front perspective view of a preferred embodiment of ahydraulic power unit 10. The hydraulic power unit 10 comprises ahydraulic fluid reservoir 12 containing a hydraulic fluid. For optimumperformance and system life, hydraulic fluid with anti-wear properties,rust and oxidation inhibitors, foam inhibitors and good stability mustbe used. Examples of premium grade hydraulic oils are Chevron Rando HDZ,Mobil DTE 10, DTE 20 series, AMSOIL, and Shell Tellus. The hydraulicfluid reservoir 12 has a pair of control valves 14, 16 and a pair ofrelief valves 18, 20. The hydraulic fluid reservoir 12 is connected witha hydraulic cylinder 22 (See FIG. 2) with a rod end 44 and a bore end46. The hydraulic cylinder 22 has a piston 24 positioned inside. A pump26 operated by a motor 28 is connected with the hydraulic fluidreservoir 12. The pump 26 pumps the hydraulic fluid from the hydraulicfluid reservoir 12 to the hydraulic cylinder 22.

A battery 30 (See FIG. 6) is connected to the hydraulic power unit 10 bymeans of a start solenoid 32. The start solenoid 32 transfers power fromthe battery 30 to the motor 28 of the hydraulic power unit 10. A digitalremote 34 is further connected to the hydraulic power unit 10 and thebattery 30 through the start solenoid 32. The digital remote 34 has adigital display 38 that registers available battery power in voltsduring upstroke and down stroke of the hydraulic power unit 10. Thedigital remote 34 informs the operator when the available power isinsufficient to operate the hydraulic power unit 10.

Turning to FIG. 2, a side perspective view of the preferred embodimentof the hydraulic power unit 10 is illustrated. The pair of controlvalves 14, 16 includes a load holding valve 14 and a directional controlvalve 16. The load holding valve 14 checks the rod end 44 and the boreend 46 of the cylinder 22. A square coil 48 in the load holding valve 14allows retracting of the cylinder 22. The directional control valve 16controls the direction of the hydraulic fluid. By activating a roundcoil 50 of the directional control valve 16, the flow path of the fluidis changed.

The pair of relief valves 18, 20 includes a primary relief valve 18 anda secondary relief valve 20. The relief valves 18, 20 prevent overpressurization of hydraulic power unit 10. The secondary relief valve 20is placed after the primary relief valve 18 to prevent thermal expansionand over pressurization of cylinder 22 which may result in catastrophicfailure.

FIGS. 3-4 illustrate perspective and sectional views of the digitalremote 34 connected to the hydraulic power unit 10. The digital remote34 includes a circuit board 36, a digital display 38, an up button 40and a down button 42. Pressing the up button 40 provides voltage readingacross the battery 30 (See FIG. 6) during the upstroke of the hydrauliccylinder 22. Pressing the down button 42 provides the voltage readingduring the down stroke of the hydraulic cylinder 22.

FIG. 5 is a schematic diagram of the hydraulic power unit 10. Forassembling the hydraulic power unit 10 the motor 28 is connected to thepump 26. An inlet 52 of the pump 26 is then connected to the reservoir12 and an outlet 54 of the pump 26 is connected to the rod end 44 of thecylinder 22 via the directional control valve 16. The bore end 46 of thecylinder 22 is connected to the reservoir 12 via the load holding valve14. The outlet 54 of the pump 26 is connected to the reservoir 12 via apair of relief valves 18, 20.

FIG. 6 is a schematic diagram illustrating the electrical connectionsbetween the hydraulic power unit 10 and the digital remote 34. Thebattery 30 is connected to the motor 28 via the start solenoid 32. Thedigital remote 34 is connected to the hydraulic power unit 10 via thedirectional control valve 16 and the load holding valve 14 and to thebattery 30 through the start solenoid 32.

Pressing the up button 40 on the digital remote 34 provides batterypower to the start solenoid 32, the motor 28 and the round coil 50 atthe same time. When the start solenoid 32 is activated, power isprovided to the motor 28 which turns the pump 26 to build pressure. Whenthe round coil 50 is activated, the directional control valve 16 shiftsallowing fluid to travel through the normally closed 2-way section ofthe load holding valve 14 and a first port 56 which will extend thecylinder 22. When the pump 26 is building pressure to extend thecylinder 22 the load holding valve 14 is opened to allow fluid from rodend 44 of the cylinder 22 to travel back to reservoir 12. When thecylinder 22 reaches the end of its stroke or maximum load fluid willbypass to the reservoir 12.

Pressing the down button 42 on the digital remote 34 provides power tostart solenoid 32, the motor 28 and square coil 48. When the startsolenoid 32 is activated power is provided to the motor 28 which turnsthe pump 26 to build pressure. Fluid flows through the directionalcontrol valve 16 then through the lower section of load holding valve 14and through a second port 58 retracting the cylinder 22. When the squarecoil 48 is energized opening the normally closed 2-way section of theload holding valve 14 allowing fluid to return through directionalcontrol valve 16 and back to the reservoir 12. When the cylinder 22reaches the end of its stroke fluid bypasses to reservoir via thesecondary relief valve 20. The secondary relief valve 20 is in place toprevent over pressurization of rod end 44 of cylinder 22 and thermalexpansion.

Continuous usage of the hydraulic power unit 10 causes low voltage atthe battery. Low voltage causes high current to be drawn from thebattery 30 which produces heat and reduce the speed of the motor 28. Lowvoltage causes carbon buildup on contacts of the start solenoid 32, theround coils and causes failure of the directional control valve 16.

Pressing the up button 40 of the digital remote 34 provides voltagereading across the battery 30 during the upstroke of the hydrauliccylinder 22 and pressing the down button 42 provides the voltage readingduring the down stroke of the hydraulic cylinder 22. The hydraulic powerunit 10 normally employs a 12V or 24V battery. In the case of a 12Vbattery the optimal operation is from 12.5V to 8V and potential failuremay occur at less than 8V. In the case of a 24V battery the optimaloperation is from 24.5V to 16V and potential failure may occur at lessthan 16.5V. The digital remote 34 includes the digital display 38 thatindicates a minimum voltage at which the usage of hydraulic power unit10 may be discontinued and the battery 30 recharged.

The presently disclosed hydraulic power unit 10 with voltage detectionis advantageous because it provides the status of the battery 30 in realtime when operating the hydraulic power unit 10. The digital remote 34registers the minimum voltage across the battery 30 and prevents arcingacross the contact points. The presently disclosed hydraulic power unit10 allows the user to determine when the operation of the hydraulicsystem should be stopped, when the battery needs to be charged andthereby prevent damage to the start solenoid, the motor, and eliminate afire hazard.

The foregoing description of the preferred embodiment of the presentinvention has been presented for the purpose of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise form disclosed. Many modifications andvariations are possible in light of the above teachings. It is intendedthat the scope of the present invention not be limited by this detaileddescription, but by the claims and the equivalents to the claimsappended hereto.

What is claimed is:
 1. A voltage detector assembly employed in hydraulicsystems, comprising: a hydraulic power unit comprising: a hydrauliccylinder having a piston, the piston positioned inside the hydrauliccylinder; a hydraulic fluid reservoir containing hydraulic fluid, thehydraulic fluid reservoir having a pair of control valves and a pair ofrelief valves, the hydraulic fluid reservoir connected with thehydraulic cylinder; and a pump operated by a motor connected with thehydraulic fluid reservoir, the pump pumps the hydraulic fluid from thehydraulic fluid reservoir to the hydraulic cylinder; a battery connectedto the hydraulic power unit by means of a start solenoid, the startsolenoid transfer power from the battery to the motor of the hydraulicpower unit; and a digital remote having a circuit board, a digitaldisplay, an up button and a down button, the digital remote connected tothe hydraulic power unit and the battery through the start solenoid, thedigital display registers available battery power in volts duringupstroke and down stroke of the hydraulic system.
 2. The voltagedetector assembly of claim 1 wherein the pair of control valves includesa load holding valve and a directional control valve.
 3. The voltagedetector assembly of claim 1 wherein the pair of relief valves includesa primary relief valve and a secondary relief valve.
 4. The voltagedetector assembly of claim 1 wherein pressing the up button providesvoltage reading across the battery during the upstroke of the hydrauliccylinder.
 5. The voltage detector assembly of claim 1 wherein pressingthe down button provides the voltage reading during the down stroke ofthe hydraulic cylinder.
 6. The voltage detector assembly of claim 1wherein the battery may be selected from a group of: 12 volt and 24volt.
 7. The voltage detector assembly of claim 1 wherein the digitaldisplay indicates a minimum voltage at which the usage of hydraulic unitmay be discontinued and the battery recharged.
 8. The voltage detectorassembly of claim 1 allows the user to determine when operation of thehydraulic power unit should be stopped.
 9. A method for assembling asystem for detecting voltage in hydraulic systems comprising the stepsof: a) connecting a motor to a pump having an outlet; b) connecting areservoir to the pump; c) connecting the pump to a cylinder via adirectional control valve; d) connecting the cylinder to the reservoirvia a load holding valve; e) connecting the outlet of the pump to thereservoir via a pair of relief valves; f) connecting a battery to themotor via a start solenoid; and g) connecting a digital remote to thedirectional control valve, the load holding valve and the batterythrough the start solenoid.
 10. The method of claim 9 wherein the startsolenoid transfers power from the battery to the motor.
 11. The methodof claim 9 wherein the digital remote includes a circuit board, adigital display, an up button and a down button.
 12. The method of claim11 wherein pressing the up button provides voltage reading across thebattery during the upstroke of the hydraulic cylinder.
 13. The method ofclaim 11 wherein pressing the down button provides the voltage readingduring the down stroke of the hydraulic cylinder.
 14. The method ofclaim 9 wherein the digital display indicates a minimum voltage at whichthe usage of hydraulic unit may be discontinued and the batteryrecharged.